There have been various known techniques of restraining occupants of motorcycles with airbag apparatuses. For example, known techniques includes a technique of restraining an occupant with an airbag inflated by inflation gas in a frontal collision (e.g., refer to Japanese Unexamined Patent Application Publication No. 10-35564). The airbag apparatus disclosed in Japanese Unexamined Patent Application Publication No. 10-35564 has a structure in which the airbag apparatus and the vehicle body (body frame) are connected with a tether, and the tether extends with the deploying motion of the airbag to retain the airbag.
In the airbag apparatus described in Japanese Unexamined Patent Application Publication No. 10-35564, the tether is housed in position with part of the tether, that couples the airbag apparatus with the vehicle body, in a loose state before the activation of the airbag apparatus. With this arrangement, the tether is loosened irregularly when the airbag is housed. Accordingly, the extending motion of the tether from the loose state with the deployment of the airbag at a frontal collision may exert an influence on a desired deploying motion of the airbag.